The C chart measures the number of non-conformities (discrepancies or defects) in an inspection lot. The C chart requires a constant sample size.

Data Available

N = 1

R(1..K) = Number of defects in each subgroup

K = Inspection Quantity

To be calculated:

Process Average Number Non conformities,

  =  

Sigma

SC =

Center Line and Control Limits

Center Line ( CLC ):
Upper Control Limit (UCLC):	CLC + 3 SC
Lower Control Limit (LCLC):	MAX(0,(CLC – 3 SC))

More information

SPC chart calculations.

---